Mac: Fix resizing of composited background tabs.
Mac: Fix resizing of composited background tabs.

BUG=54842
TEST=Have an composited tab be a background tab. Resize window larger. Switch to composited tab. It should have the new size.

Review URL: http://codereview.chromium.org/3528019

git-svn-id: dd90618784b6a4b323ea0c23a071cb1c9e6f2ac7@62026 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser,wistoch/meego-app-browser